OMV Austria E&P GmbH operates 26 oil fields in Lower Austria. The majority was developed in the 1950s and 1960s and shows an extended decline period. The challenge of operating brown fields is seen to maintain a reasonable oil production over time in a cost effective manner - this can be tackled by a major chemical enhanced oil recovery field redevelopment project. The scope of the polymer field rollout is to create and efficiently operate horizontal polymer injection patterns in two horizons in Lower Austria. OMV follows the strategy to pilot new reservoir and production technologies before their application in field rollouts. Due to the large project investment volume it is crucial to derive information and lessons learned from existing pilot patterns to optimize conceptual decisions on artificial lift, completion, sand control and injection strategy and to reduce technical risk. In the past 10 years several vertical pilot patterns were created to analyze the efficacy of polymer injection in the Tortonian Horizon. Significant operational experience in water treatment, polymer injection and polymer back production, but also in tracer testing was established. Since already the vertical polymer patterns showed not only operational success, but also significant incremental oil production, the idea of horizontal flooding patterns was born. To confirm and understand the impact of polymer injection also in horizontal wells, a first horizontal pilot pattern was drilled; additional pilot wells are currently following. For a future field redevelopment the technology selection should be de facto based on either standard or pilot-proven technologies. This paper describes measures undertaken in the discipline of production technology to prepare for one of the largest field redevelopment projects in the history of OMV Austria. These measures include the application of several pilot projects in the field of artificial lift, completion design and sand control, production and injection allocation. Therewith production technology serves the needs for active reservoir management and thus, follows a holistic field development approach.
Summary Horizontal wells are frequently used to increase injectivity and for cost-efficient production of mobilized oil in polymer-augmented waterfloods. Usually, only fluid and polymer production data at the wellhead of the production well are available. We used inflow tracer technology to determine changes in hydrocarbon influx owing to polymer injection and to determine the connection from various zones of the horizontal injector to the horizontal producer. Inflow tracer technology was introduced in horizontal polymer injection and production wells. In the production wells, tracers are released when they are contacted by water and oil. Oil and water tracer systems were used in the horizontal production wells. The changes in the observed tracer concentration were used to quantify changes in influx from various sections of the horizontal producers owing to polymer injection. The inflow tracer technology applied in the horizontal injection wells demonstrates connectivity between different sections of the injection wells and two surrounding vertical and horizontal production wells and opens the usage of this technology for interwell water tracer applications. Inflow tracer technology enables one to elucidate the inflow from various sections of the horizontal wells and the changes thereof, even quantifying changes in influx of various fluids (oil and water). The information shows which sections are contributing and the substantial changes in the influx of oil from the various zones due to polymer solution injection. The overall incremental oil could be allocated to the various horizontal well sections based on the tracer results. Even zones that almost exclusively produced water before polymer injection showed a significant increase in oil influx. The inflow tracer technology installed in the injection well allowed us to analyze the connectivity of the injector to producer not only globally but spatially along the horizontal well. These data are used for reservoir characterization, to condition numerical models, and for reservoir management. Conventional interwell tracer technology allows one to determine the connectivity and connected volumes of horizontal well polymer field developments. However, it reveals neither information about influx of the sections nor the connectivity of various sections of the horizontal wells. Inflow tracer technology closes this gap; it allows one to quantify changes in influx of the fluids. Furthermore, the newly developed installed injection well tracer technology gives spatial information about the connectivity of the horizontal well sections.
OMV Austria E&P GmbH is currently focusing on a major chemical enhanced oil recovery redevelopment project for a mature oil field within the Vienna Basin. Cost-effective and flexible artificial lift systems (ALS) for new and existing production wells within the planned polymer patterns are seen to be crucial for the economic success of this project. The selected ALS must be capable of dealing with changed fluid properties due to back produced polymer and achieve the target production rates with a reasonable run life. Prior to final selection and following field rollout, the production capabilities of the selected ALS must be demonstrated. Field experience and an extensive testing program supplied most essential information and data for the necessary design adaptations for future polymer back producing wells. The ALS were screened according to their rate capabilities and flexibility, OMV Austria's in-house experience, necessary surface networks and design constraints. Uncertainties regarding reservoir and production system behaviors in a future enhanced oil recovery (EOR) full-field application were identified. A literature review showed that there is only limited information available about the required adaptations and mitigation measures for the pump designs for polymer back producing wells. The consecutive risk assessment demonstrated the necessity of testing the pump performance in the in-house laboratory, OMV Austria's fields, and pump test facilities sponsored by OMV. Existing polymer pilot patterns are used to derive information and lessons learned, which are continuously implemented in the artificial lift basis of design for the field rollout. The effects of chemical and rheological behavior of the polymer solution on the production system were analyzed and clearly demonstrated the complexity of handling non-Newtonian fluids. The combination of all requirements described above resulted in the decision to select electrical submersible pumps (ESPs) and sucker rod pumps (SRPs) as the desired artificial lift methods. The ESP test facility gives clear indications for severe derating of the pump performance when pumping polymer. The polymer ESP pilot wells are providing the most realistic input data, feeding into the final pump and motor design. The influence of polymer concentration on SRPs was shown with polymer spiking tests and a SRP test facility. From field experience several conclusions on the properties of the back produced polymer could be derived. Especially the degree of mechanical degradation of the polymer solution is essential for the artificial lift designs. Also, challenges regarding aspects of flow assurance were experienced; their reasons and potential remedies are currently analyzed in the laboratory. This paper describes the selection, testing program and pilot experience of ESPs and SRPs under the most realistic conditions within OMV Austria. The necessary design adaptations due to the chemical and rheological behavior of the back produced polymer are identified. The sum of all test activities should prepare OMV Austria for one of the largest field redevelopment projects in its history.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.